Astrology already accounts for designated patterns of why someone would relate or not vibe with their sun sign. The most important of these is the position of the inner planets, which describe parts of our personality that are present, but less focused on discussing direct things like our ego and our emotions, pieces that are more personal or obvious to us.

Even more so, because of simple astronomy, we already know specifically why so many people feel aligned with a sign adjacent to their sun sign. Not just any other sign, but exactly the ones highlighted by The Cusp – the signs bookending their sun sign.

The inner planets’ relatively similar orbital rates and close positions mean that, unless recently interrupted by a retrograde, they often tend to clump up in the same few zodiac signs, and from Earth’s vantage point this is often pretty close to the location of the Sun. In natal charts, this means that it is very common for people to have a stellium (three or more placements) that falls in the sign adjacent to their sun sign.

Cusp babes, as said by the “general cusps,” tend to fall on days when the Sun has recently changed signs (clearly.) But there’s something else important about this. Usually, when the Sun has changed signs, the inner planets change signs, have already changed signs, or are about to change signs as well.

Basically, the planets and Earth are all moving around the Sun at different rates. The inner planets – Mercury, Venus and Mars – orbit the sun on rates that are even marginally similar to Earth’s and all of their distances are similarly much, much closer to the Sun than all those other guys. The gap between Mars and Jupiter alone could fit several more sets of Mercury, Venus, and Earth between them.

This means that within the scope of one Earth year, one revolution of the Earth around the Sun, the inner planets cover quite a bit of ground in the zodiac. Because the zodiac is a geocentric system of mapping the sky in relation to Earth, the ground they cover in the zodiac is quite similar to that of the Sun. The illusion of retrograde motion additionally makes them track closer to the Sun through the zodiac. The outer planets, being much further away and taking more time on the scale of an Earth year to cover the same ground in the zodiac, move at rates more like tens of Earth solar years. Jupiter itself, the next closest one, takes over a dozen Earth years to clear the entire zodiac wheel.

The result, in astrology? It is exceedingly common for people to have one or more inner planet in the sign next to their sun sign. Some people even have all three, which alone is a forceful stellium that can displace much of their visible characteristics and traits onto that sign. If you have three major planets in Libra, you’re going to feel a bit like a Libra to other people. You have very defined and wide-ranging traits that are absolutely informed and described by the energy of Libra, and that’s a totally legitimate interpretation of the chart.

It’s worth nothing that each year, based on outer planet movements and retrogrades, having a stellium in a particular sign is more or less common for given signs. That’s because outer planets can make up stelliums as well. For example, in a year when Jupiter is in Virgo and no inner planet retrogrades occurred within a few months’ radius, Virgos and possibly Leos or Libras might commonly see Virgo stelliums occur in their birth charts.

Another rarer example would be when two outer planets conjunct or pass in a sign, such as the Uranus/Neptune rendezvous in Capricorn around the early 90s. Many millennials born in the winter of affected years have supercharged Capricorn from the abundance of planets in that region of our zodiac at the time. It has a magnetic pull on the place of the chart where it falls, since two heavyweight planets are holding it down. For someone who already has a lot of activity in the sign, the stelliums get enormous – I have seen Sagittarians, Capricorns, and Aquarians from the time period with 5 planet stelliums in Capricorn. It affects each chart a different way, but it always has an effect. Something similar will happen with an upcoming conjunction of Pluto and Saturn just a few years from now – some Capricorns, some Aquarians, and some Pisces born in that span of time will be very, very Aquarian, and lots of children born in those years will have a similar magnet on the part of their chart that holds the degrees of Aquarius.

What does having a stellium mean, though?

When this does happen, and someone DOES have a stellium in an adjacent sign, made up of inners, outers, or some combination, they obviously approach the venues of those planets (and the regions of the affected houses) in ways ruled by that sign. This is the case for everyone, but the weight and proportion of traits ruled by one sign will change according to the number of planets. For people with significant or very affective personal stelliums, the line becomes blurry – how much of their personality is ruled by one sign, their Sun sign, or the other, their stellium?

Astrological interpretation is meant to suss out these differences and explain them fully. This is why you need someone who can actually read the chart, take stock of what’s there, and interpret it based on their knowledge – someone who can understand what it’s trying to tell you about yourself and your path, your roles and your opportunities. The chart, when read thoroughly, describes very clearly what traits belong where and how they can manifest. Like reading any planet, the traits of the sign and planet and house and any aspects or important movements it makes will affect what it has to stay. A stellium just adds a gravity to the energies in their corner, and can give someone an air or a flavor of a different sign.